1. Field of the Invention
The present invention relates to an organic light emitting display device and a driving method thereof.
2. Discussion of Related Art
In recent years, various flat panel displays, which have reduced weight and volume compared to cathode ray tubes, have been developed. In particular, organic light emitting diode display devices have attracted public attention, because the organic light emitting diode display devices have an excellent luminance and color purity since organic compounds are used as light emission material.
Such an organic light emitting display device is expected to be effectively used for portable display devices and the like, since it is thin and lightweight and driven at a low electric power.
However, conventional organic light emitting display devices emit light with a constant luminance regardless of surrounding brightness, and therefore their visibility is varied according to the surrounding brightness even if an image is displayed with the same gray levels. For example, an image, which is displayed when the surrounding brightness is high, has a reduced visibility, compared to an image displayed when the surrounding brightness is low.
Also, in conventional organic light emitting display devices, the amount of electric current that flows to a display area increases as the number of pixels that emit the light during one frame period increases. Further, if there are pixels among the light-emitting pixels, that display high gray levels, a larger amount of electric current flows to the display area, resulting in increased power consumption.